# std::boolalpha, std::noboolalpha

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< cpp‎ | io‎ | manip

Defined in header `<ios>` |  |
std::ios_base& boolalpha( std::ios_base& str ); | (1) |
std::ios_base& noboolalpha( std::ios_base& str ); | (2) |

1) Enables the `boolalpha` flag in the stream str as if by calling str.setf(std::ios_base::boolalpha).
2) Disables the `boolalpha` flag in the stream str as if by calling str.unsetf(std::ios_base::boolalpha).

`std::boolalpha` is an I/O manipulator, so it may be called with an expression such as out << std::boolalpha for any `out` of type std::basic_ostream or with an expression such as in >> std::boolalpha for any `in` of type std::basic_istream.

### Parameters

str | - | reference to I/O stream

### Return value

str (reference to the stream after manipulation).

### Example

Run this code

    #include <iostream>
    #include <sstream>

    int main()
    {
        // boolalpha output
        std::cout << "default true: " << true << '\n'
                  << "default false: " << false << '\n'
                  << std::boolalpha
                  << "boolalpha true: " << true << '\n'
                  << "boolalpha false: " << false << '\n'
                  << std::noboolalpha
                  << "noboolalpha true: " << true << '\n'
                  << "noboolalpha false: " << false << '\n';

        // boolalpha parse
        bool b1, b2;
        std::istringstream is("true false");
        is >> std::boolalpha >> b1 >> b2;

        std::cout << '"' << is.str() << "\" parsed as: "
                  << std::boolalpha << b1 << ' ' << b2 << '\n';
    }

Output:

    default true: 1
    default false: 0
    boolalpha true: true
    boolalpha false: false
    noboolalpha true: 1
    noboolalpha false: 0
    "true false" parsed as: true false

### See also

resetiosflags | clears the specified ios_base flags (function)
setiosflags | sets the specified `ios_base` flags (function)
do_truenamedo_falsename [virtual] | provides the string to use as the name of the boolean true and false (virtual protected member function of `std::numpunct<CharT>`)

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